Forking and planting spacing impacts on wood density, X-ray density, and heartwood proportion of Tachigali vulgaris

Key message In Tachigali vulgaris planting, the 3.0 × 3.0 m spacing reduced variability in wood properties and increased the proportion of medium-density wood, while forking increased the proportion of low-density wood. Promising Amazonia species for forest energy crops require further investigation into how silviculture affects wood quality. This study sought to investigate how planting spacing and stem type (forked and non-forked) affect the basic wood density, X-ray density, and heartwood development of Tachigali vulgaris in a homogeneous plantation in Amazonia. The experiment was established with initial planting spacings of 3.0 × 1.5 m, 3.0 × 2.0 m, 3.0 × 2.5 m, 3.0 × 3.0 m, 3.0 × 3.5 m, and 3.0 × 4.0 m. 102-month-old trees were harvested for the work. Disks sampled along the stem height were tested for wood basic density and density measured by X-ray densitometry (air-dry density by growth ring) analyses. Disks obtained at the 1.3 m height were photographed and submitted to image manipulation for heartwood/sapwood analysis. The lowest average wood density was 0.512 g cm −3 in the 3.0 × 1.5 m spacing, and the highest was 0.538 g cm −3 in the 3.0 × 4.0 m spacing. Among non-forked trees, 66% had medium-density (≥ 0.500 g cm −3 ) and 34% low-density (